This Bioengineering Research Partnership (BRP) will conduct basic research to improve biocompatibility of materials used in biomedical devices such as prostheses and implants by providing a higher level of cleanliness and decontamination, while simultaneously providing sterilization. The BRP will determine the effectiveness of dense phase (liquid or compressed gas) carbon dioxide fluid technology for enhancing biocompatibility. The multidisciplinary partnership is led by the Department of Chemical Engineering at the University of South Carolina and includes two university partners; the Medical University of South Carolina and Clemson University, assisted by outside experts on surface preparation of implants and industrial applications of supercritical fluid based technology. A three-year BRP effort is proposed: Year 1 will confirm whether, and under what conditions, dense phase CO2 is an effective medium for sterilizing and cleaning common biomaterials and will focus on simple solid metallic, polymer, or ceramic coupons, using three typical microorganisms for tests of sterilization effectiveness and by processing samples that have been contaminated with known particulates (graphite, polyperfluoroethylene, and iron oxide) to determine the effectiveness of particulate removal and cleaning. Finally, tests to determine whether the materials treated with CO2, show improved resistance to bacterial adhesion and biofilm formation will be conducted. Year 2 research will focus on complex materials, namely flexible polymers (polyurethane and silicone rubber), as well as porous monoliths of titanium. Also in Year 2, the BRP will examine the material surface to search for adverse effects of CO2 processing, such as corrosion, pitting, and embrittlement. These experiments provide data needed for process optimization and permit comparison to known material/surface damage caused by existing cleaning and sterilization methods. Year 3 will focus on process design and optimization through the use of process design models and testing of representative devices (artificial joint, stent, and catheter) with CO2 under optimized conditions and determine the integrity and biocompatibility of the device. Also during Year 3, the ability of C02 processing to clean, decontaminate, and sterilize will be tested in vitro for material biocompatibility using cell culture methods and in vivo for histocompatibility using a subcutaneous implantation animal model.